1. Field of the Invention
The invention concerns an adaptive sensory-motor encoder as well as a spinal implant and a cranial implant.
2. Description of Related Art
There are several precursor systems of spinal implants known, that, for example, are employed in cases of transverse lesions of the spinal cord with paraplegia for control of urinary tract functions and for guidance of ambulating movements or grasping movements that work by means of stimulation contacts in the form of implants or that work transcutaneously (see Eckmiller and colleagues., Neurotechnology Report, 1994 and 1995).
The spinal implant precursors currently available or those in development have diverse limitations, for example, no adaptation, no functional increase of number of microcontacts and no bi-directional, perception-based control by the implant carrier.
In particular, the currently developed microcontact structures and signal and energy transfer systems operate unidirectionally from the external encoder to the implanted stimulator and therefore offer no possibility of ongoing monitoring of neural impulse activity of the stimulated neurons. Thus, the stimulation pulse sequence cannot be adapted to the spontaneous activity of the neurons. Furthermore, triggering of neurobiological impulses by stimulation pulses can not be monitored directly. Moreover, an assured impulse monitoring opportunity for possible temporal tuning and synchronization of the impulse sequences of multiple neurons is also lacking.
There are isolated rationales for development of implanted, active substance applicators that are controlled by need, for example for insulin, but there have been to date no cranial implants that have been successfully implemented. Cranial implants that, for example, are urgently needed for local, event-triggered administration of active substances for suppression of onset of epileptic events, are not available.
This invention undertakes to eliminate the foregoing problems and to create an adaptive, sensory-motor encoder, which with the aid of neural networks in dialogue with the implant carrier or in bi-directional signal and data exchange from implant and addressed nerve tissue, can perform an optimization of the perturbed nervous system functions, functionally increases the selectively reachable stimulation sites, and monitors the neural activity of individual neurons that are to be stimulated. The invention further seeks to create a process for the operation of an adaptive sensory-motor encoder, and further to provide a spinal implant and a cranial implant.
This problem is solved by an encoder with the characteristics described herein.
Because the encoder is bi-directionally coupled with implanted microcontacts, monitoring of the neural impulse activity of individual neurons to be stimulated and other signals and the execution of quasi-autonomous actions can be realized. The functions can be optimized either self-actuating by the neural network or in dialogue with the implant carrier. The number of the selectively addressable stimulation sites can be functionally increased and the neural activity of individual neurons monitored. The implanted structure can operate sensory-motor quasi-autonomously by using appropriate sensory and action components and an adaptive control system. Essential components and processes of the adaptive information processing system are implemented in various combinations, particularly for spinal implants in bi-directional contact with the spinal cord or the peripheral nervous system and for cranial implants in bi-directional contact with the structures of the central nervous system within the cranium.
Furthermore, for the first time an encoder is proposed that allows the number of selectively reachable stimulation sites to be functionally increased and also subsequently to adapt itself to new stimulation conditions. The encoder described herein can (on the basis of its structure and function as a group of adaptive spatio-temporal filters) in addition to the stimulation function, also perform monitoring an evaluation of the neural activity of the neurons to be stimulated.
The spatio-temporal filters associated with the individual microcontacts, to the extent possible, are tuned to optimum function individually in the dialogue between the encoder and the implant carrier.
In contrast with an encoder with static pre-processing; that is, without the possibility of individual adjustment, the present case allows, on the basis of the single relevant criterion; namely the specific functional enhancement of the given area of the nervous system, adjustment of the single spatio-temporal filters as separate encoder channels. This advantage includes the possibility that subsequent function changes, for example, as a result of shift of micro-contacts by corresponding adaptations of the spatio-temporal filter function, can be compensated for. An advantage of the tuning of the spatio-temporal filter function in the dialogue with the implant carrier or with an area of the carrier""s nervous system is in the consideration of functional aspects, that only the actual implant carrier can incorporate into the optimization process and only in implicit form; namely, for example, by subjective assessment of his perception or by evaluation and function monitoring of his nervous system and their use in the encoder adjustment.
The asynchronous impulse sequences of the individual spatio-temporal filter outputs of the functionally separated encoder channels, as stimulation signals, selective stimulation sites are selectively tuned to one another in the dialogue with the implant carrier, in consideration of the of the neural impulses recorded at the stimulation site.
Because it is presumed that time courses and locale distributions of the stimulation signals that have been reciprocally tuned by superposition, have been suitably selected by an adaptation process and their field distributions effected at several microcontacts will, as stimulation foci, trigger local and temporal selective neural impulse excitations, the number of selectively addressable stimulation sites and their definition or cross-talk suppression will be functionally enhanced with fixed number of implanted microcontacts.
With a given, relatively low number of implanted and permanently functional microcontacts, whose position relative to the neurons can not be modified, it is of particular advantage, functionally; that is, by generation of suitable signals, to increase the number of selectively reachable stimulation sites or neurons and thus, at the same time, increase the number of separately accessible encoder channels with an adequate reserve of spatio-temporal filters. This advantage effects an improvement of the quality of the respective function.
The control or relief of defective functions of the spinal cord or peripheral nervous system with the aid of a partially implanted neuroprosthesis in the closest possible sensory and motor coupling with the implant carrier and by using quasi-autonomous sensory-motor functions of the implanted structure is thus made possible.
Using adaptive spinal implants the quality of the relief from functional impairments in the spinal cord or peripheral nervous system fundamentally improved and, with respect to diverse applications, is possible for the first time.
Alleviation of neural functional impairments of the central nervous system within the cranium is made possible, particularly for the purpose of reducing undesirable sensory, motor, or cognitive effects for a number of groups of neurological or psychiatric patients using an implanted structure with an active substance applicator and quasi-autonomous, sensory-motor functions in coupling with control and monitoring functions of the implant carrier.
For the first time, using adaptive cranial implants the quality of the relief of neural functional impairments in the central nervous system within the cranium is possible in diverse applications.